The therapeutic use of thermal blankets having walls of flexible polymeric material that are sealed together to define a labyrinth of passages for the circulation of heating or cooling fluid is well known. While such therapy may involve either heating or cooling portions of the body, it is the cooling mode that in recent years has received particular attention because of its effectiveness in post-operative treatment and in connection with physical therapy. In particular, cold therapy following soft tissue trauma has been shown to reduce pain, swelling, blood loss, inflammation and hematoma formation. During the rehabilitative process, cold therapy has been utilized effectively to diminish inflammation and patient discomfort.
It has been found that two factors bearing on the effectiveness of cryotherapy are the rate of cooling of the treatment site and the capability of maintaining a preselected and constant cold temperature. Variations in the rate of cooling and in maintaining a constant temperature may be due to the type and amount of gauze placed between the thermal blanket and the treatment site. Ideally, the interface between a thermal blanket and a treatment site should promote, or at least not retard, rapid cooling of the site to a selected treatment temperature which may then be maintained without substantial variation throughout the period of treatment.
It has also been found that variations may occur because of differences in the amounts of fluid exuding from a wound or treatment site and the capacity of the dressing material to absorb that fluid. Frequent changing of a dressing is often necessary, particularly during the early post-operative period, and it is therefore important that the dressing interface be non-adherent as well as non-linting and absorbent. Over the duration of treatment, a gauze pad or other dressing material is normally replaced numerous times whereas a single thermal blanket is commonly used and reused throughout the treatment period.
An important aspect of this invention lies in providing a disposable interfacing pad for a reusable thermal blanket that has significantly higher thermal conductivity than conventional gauze pads or dressings while, at the same time, providing substantial fluid absorbency. When used to cover an exuding wound, the interfacing pad of this invention demonstrates a capacity to absorb and retain a large volume of fluid, drawing it away from the wound while at the same time maintaining a moist environment and a non-adhering and non-linting contact surface for promoting wound healing. Such advantages are achieved by means of a relatively thin multi-layer pad which makes direct contact both with the wound and its surrounding skin areas and with the surface of the thermal blanket.
In one embodiment of the invention, the multi-layer pad is generally U-shaped in outline and may be easily folded or formed to surround an incision or wound site at knee or shoulder locations. It comprises at least three layers, namely, a porous, fluid-transmitting and preferably fluid-absorbing facing layer, a thin, flexible, fluid-impervious backing layer, and an intermediate or core layer composed of a hydrocolloid-containing skin barrier material having both wet and dry tack. The pad has essentially the same configuration as the thermal blanket with which it is used and has a surface area at least as large, and preferably larger than, the surface area of the blanket. Passages extend through the blanket for the circulation of cold (or hot) thermal fluid, and the wall of the blanket facing the pad provides a smooth surface for releasable adhesive attachment to the backing layer of the interfacing pad. Adhesive attachment means in the form of one or more pressure-sensitive adhesive patches releasably secure the blanket and pad together. Ideally, the patches are carried by the blanket and have substantially greater affinity for the polymeric material of the blanket wall than for the (material of the pad's backing layer, thereby promoting a clean separation of the adhesive from the backing layer when replacement of an interfacing pad is required.
In one embodiment of the invention, the porous, fluid-transmitting facing layer of the pad may be provided with apertures or openings through which surface portions of the hydrocolloid-containing intermediate layer are exposed. Such exposed portions of the adhesive intermediate layer may be brought into direct contact with skin surfaces about a wound or incision site for helping to hold the pad (and blanket) in a selected location and shaped condition.
Most advantageously, the intermediate or core layer of skin barrier material contains, in addition to at least one water-absorbing particulate hydrocolloid and a water-insoluble dry-tack-providing elastomer such as polyisobutylene, a copolymer resin capable of being cross linked when the composition is subjected to ionizing irradiation to form a cross-linked polymer network, as disclosed in co-owned U.S. Pat. No. 4,477,325, since such a skin barrier composition when used herein results in an interfacing pad capable of absorbing relatively large amounts of fluid without losing cohesive strength and disintegrating.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.